Mineral wool is produced for use in numerous applications, such as sound insulation, heat insulation, fire protection, construction applications and as a horticultural growth substrate. In order to produce mineral wool it is necessary first to form a mineral melt, from mineral materials, and to form this melt into fibres. The mineral materials can be in the form of crushed rock or other large size material, but it is also in some processes important to provide the mineral materials as small particles.
For instance, it is common to provide at least part of a raw material charge in the form of bonded briquettes formed of a relatively small size particulate materials bonded together with a binder, which is commonly cement. These small size particle materials can for instance be waste materials from industrial processes, milled waste mineral wool itself and virgin raw materials having small particle size, such as various types of sand.
It is known to use waste mineral fibres themselves as materials for inclusion in such briquettes.
The inclusion of raw materials in lump or briquette form is usually done when the mineral melt is produced in a shaft furnace such as a cupola furnace. There are other means of generating a melt, for instance in a tank furnace or in a cyclone furnace (such as described in WO 0302469), or in an electrical furnace. In these methods it is not necessary that the raw materials are in large particle form but instead they may be in the form of fine particles when they are added to the relevant furnace.
It would be desirable to produce raw materials which are suitable for inclusion as raw materials in the production of mineral wool, and which are versatile enough to be able to be used as a component of briquettes, especially cement briquettes, which are the most common form of briquette used in the production of mineral fibres, and which can lead to briquettes of appropriate quality including their chemistry, density and strength. It would also be desirable if such materials were also suitable for use directly in fine particle form such as the cyclone, electrical and tank furnaces mentioned above.